Andy Eavis from the World Caving Association says the youngsters have so far been “calm and collected.”

“They were all in pretty good spirits so that suggests that these are cool customers who are capable of doing things that they have never done before without panicking.

“That obviously bodes very well for them putting on a face mask and swimming underwater – moving underwater; swimming really is not the right word.”

Thai soldiers try to connect water pipes that will help bypass water from entering ther cave where 12 boys and their soccer coach are trapped, 07-07-2018. Image: Sakchai Lalit/AP/Press Association Images

Millions of litres of water have been pumped out in recent days, but experts have warned that further downpours could shrink the unflooded space where the boys are sheltering to just 10 square metres (108 square feet).

Governor Narongsak Osatanakor warned: “Finding the boys doesn't mean we have finished our mission. It is only a small battle we have won, but the war has not ended.”

“The war ends when we win all three battles - the battles to search, rescue and send them home.”